Air-pump.



Patented Mar. l8, I902.

.1. ROBERTSON.

AI R PU MP.

(Application fllad Nov. 3, 1899.)

(No Model.)

UNITED STATES PATENT OFFICE. V

JOHN ROBERTSOBLOF CINCINNATI, OHIO.

AIR-PUMP.

SPECIFICATION forming part of Letters Patent No. 695,492,dated March 18,1902. Application filed November 3,1899. Serial No. 735,667. (No model.)

any purposesuch,for example, as repairing.

My invention consists in a pump having an open-ended barrel .orcylinder, a piston movable therein and provided with an expansi blepacking to fit the walls of the barrel or cylinder, and a cap or closurefor the open end of the barrel or cylinder having a depending flange tofit within the open end of the barrel or cylinder and adapted to housewithin it the pump-piston.

The invention also consistsin certain novel features of theconstruction, combination, and arrangement of the several parts of theimproved pump whereby certain important advantages are attained and thepump is renderedmore convenient and efficient, all as will behereinafter fully set forth.

The novel features will be carefully defined in the claims.

In the accompanying drawings,which serve to illustrate my invention,Figure 1 is asectional elevation takenthrough the barrel of an air-pumpconstructed according to my invention. Fig. 2 is an enlarged fragmentaryView showing inaxial section the cap or closure for the open end of thepump-barrel and the piston housed therein.' Fig. 3 is a sectional viewshowing the cap or closure detached, and Fig. tis an under sideelevation of the cap or closure detached.-

In these views, 1 indicates the pump barrel or cylinder, having itslower end closed by a plate 2, provided with a central threaded stem 3to screw into a base 4:, adapted to rest firmly on the floor to supportthe pump in erect position when. in use. The upper end 5 of the barrelor cylinder is open, and inside said barrel plays a piston 6, held inthelower end of a tubular rod or stem 7, the upper end 8 of which extendsabove the upper open end 5 of the'barrel and is provided with a handle9, by means of which the piston may be moved within the barrel. A nipple10 is also provided at the upper end of the tubular stem or piston-rod 7for connection with a rubber hose or the like to carry oi the air fromthe outlet-passage of the rod or stem when the pump is operated.

The piston 6 comprises a disk-shaped piston-head 11, secured on the endof the rod or stem 7 and of a less diameter than the bore of the barrel1, so that air may pass down in Fig. 2, said stem 7 having a wire 18extended across it to stop the upward movement of the valve.

19 indicates the cap for closing the open upper end 5 of the barrel 1,said cap or closure being, as herein shown, formed of a piece of metalstamped or formed up to produce an annular rim 21 to rest on the edgesof the barrel and a depending annular flange or skirt 22 to fit insideof the open end of the barrel, said flange 22 forming within it and uponthe under side of the cap or closure a circular recess to receive andhouse the piston 6 when the latter is drawn" upward to .the positionshown in Fig. 2. The top of the cap or 010- sure 19 has a centralopening 20 for the passage of thestem or rod 7 and-is alsoprovided withan opening 23 for the admission of air into the barrel when the pistonis pushed down. The cap is preferably held in place by friction;

The flexible packing 12 is made of greater diameter than the bore of thecylinder, and its edges are pressed down, as shown at 24, so as totightly engage the walls of the cylinder when the piston is pushed down,but to yield inwardly when the piston is drawn up to permit air fromabove to be drawn into the bore beneath the piston.

In operation when the piston is pushed down the air in the cylinderbeneath it is compressed and passes up through the passage 15 of screw13, lifting valve 17 so as to enter the hollow of'the rod or stem 7,from which it passes through the nipple 10 to a suitable hose or thelike. When the piston is drawn up, the valve 17 seats itself by gravityand air is drawn into the bore beneath the piston around the edges ofthe latter. When it is desired to remove the piston for purposes ofrepair or for any other reason, the piston rod or stem 7 is drawn upuntil the piston is housed within the cap or closure 19, whereupon thepiston, togetherwith the cap, may be removed from the barrel 1. Then thepiston is removed from the barrel, its packing 12 may be detached byunscrewing the screw 13, after which a new packing may be applied. lVheuit is desired to again insert the piston in the barrel, the piston, withits fresh packing, is first drawn up into the recess within the flange22 of the cap or closure 19, after which the cap is inserted in the openend 5 of the barrel, carrying with it the piston, which is thus broughtinto the barrel and may bepushed down, the edges 2% of its packingspringing out, after leaving the recess of the cap, into engagement withthe walls of the barrel. Thus it will be seen that the improved cap 19not only affords a simple and inexpensive closure for the upper end ofthe barrel, but also affords a very convenient means for inserting thepiston in the barrel and for giving the edges of the flexible packingthe proper form, thereby dispensing with a preliminary molding of thepacking and greatly facilitating the repair of the pump when the packingis worn. It will also be seen that the improved pump is capable ofconsiderable modification without material departure from the scope ofthe invention, and for this reason I do not wish to be understood aslimiting myself to the precise form and arrangement of the several partsherein set forth; nor do I desire to limit myself to the use of theimproved cap or closure upon the special form of pump herein shown,since it is apparent that the device is capable of use upon variousother forms of pump.

Having thus described my invention, I claim-- 1. In an air-pump, acup-shaped cap to receive and shape a collapsible plunger and hold it inposition while it is being inserted into the open end of the cylinder.

2. In a pump, the combination of an openended barrel or cylinder, apiston therein and provided with an expansible packing to lit the wallsof the cylinder or barrel, and a cap or closure for the barrel orcylinder adapted to fit inside of the open end thereof and having in itsunder side a cavity to receive shape and house the piston to facilitatethe inser tion thereof Within the barrel or cylinder, substantially asset forth.

JOHN ROBERTSON. Witnesses:

J AMES N. Ramsay, EMMA llny.

